The present invention relates to a new and improved construction of a clamping or chucking apparatus for a shaper cutter for a gear shaping machine, in particular a generating gear shaping machine for the fabrication of gears.
Generally speaking, such clamping or chucking apparatus comprises a ram spindle which can be axially displaced for to-and-fro movement and a cutter holder attached to one end of the ram spindle. The cutter holder is provided with a contact or abutment surface for the shaper cutter. Such clamping or chucking apparatus further comprises a centering projection which axially protrudes away from the contact surface of the cutter holder and serves for the fixing of the shaper cutter, and a chucking or clamping plate which is attached to one end of the centering projection by means of a checking or clamping mandrel. The clamping plate coacts with the clamping mandrel or plug for clamping the shaper cutter against the contact surface of the cutter holder.
With heretofore known clamping or chucking apparatuses of the above-mentioned type the cutter holder and the clamping mandrel are constructed of one piece and threaded to the ram spindle. The clamping mandrel is provided with external threads and the clamping plate with corresponding internal threads. Thus the clamping plate can be screwed to the chucking or clamping mandrel after the shaper cutter has been mounted upon the clamping mandrel, so that the shaper cutter is pressed against the contact surface of the cutter holder. In order to produce a sufficient clamping force a suitable tool having a long lever arm must be used for tightening the clamping plate. The forces which are thus applied by means of the tool in a more or less sudden or shock-like manner and the moments or torque which result therefrom are transmitted via the cutter holder to the ram spindle and load the guides and the drive gearing or transmission. Such guides and drive gearing are provided for the axial to-and-fro movements and the rotation of the ram spindle, respectively, and are fairly sensitive or delicate because of their required high accuracy in design. Especially for the re-grinding work it is necessary to dismantle the shaper cutters, so that the loads at the above-mentioned parts or elements, of the gear shaping machine, which are unavoidable with the heretofore known constructions of clamping apparatuses, occur rather frequently and can cause corresponding damage during the course of time. Furthermore, the prior art-clamping or chucking apparatuses of the type described above require a considerable downtime of the machine for dismantling and assembling the shaper cutter.